1. Field of the Invention
This invention relates to a high efficiency welding device for use with a continuous welding electrode. The device delivers the electrode towards the work piece to be welded with high welding current efficiency and precision.
2. Background of the Invention
A continuous welding electrode consists of a continuous metal core coated with a welding flux, and air gaps are formed on the flux coating in evenly spaced intervals. The metal core is exposed through the air gaps such that the electrode may be advanced with a welding device, commonly called a welding gun which has continuously moving carriers engaging with the air gaps for moving the electrode towards the working piece as well as for delivering the welding current to the metal core through the exposed air gaps. A welding operation may be continuously carried out with the welding current efficiently provided so as to produce a high quality continuous, strong, consistent, and smooth weld. Presently in welding guns, the carriers are in the form of a series of evenly spaced carriages driven with a continuous chain, belt or similar means for advancing the welding electrode forward towards the work piece as well as for delivering the welding current to the metal core through the exposed air gaps. Such construction is relatively complex in construction and the carriages are prone to jamming.
A welding gun as shown in U.S. Pat. No. 7,115,835 shows a welding gun having two reciprocating carriages located on two opposite sides of the electrode. The carriages move back and forth with respect to one another. Each carriage has a pair of clamping jaws which engage with consecutive neighboring air gaps. During the advancing of the welding electrode, one pair of the clamping jaws of a first carriage grasp the electrode at an air gap at its two opposite sides to move the electrode forward while the clamping jaws of the second carriage is opened to move backward to the position of the next air gaps. This action operates continuously and alternately for advancing the electrode forward and to supply the welding current the metal core of the electrode through the closed clamping jaws. The clamping jaws of the carriages only engage with two directly opposite sides of the electrode in a 180° plane. If the distance between the clamping jaws of the first carriage and the second carriage is “L”; and the distance between the air gaps in the electrode flux coating is “l”, in order for the system to operate properly the distance L must necessarily be larger than 2l. Thus, the welding current is only supplied to the metal core through a 2l distance or the length of the welding electrode from the work piece. The length of welding electrode contributes to a higher current resistance in reducing the efficiency of the current provided to the welding operation. Furthermore, longer carriages and driving system must be provided in the welding gun, which inherently increases the weight of the welding gun such that the gun must be held and operated awkwardly with two hands.